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Abstract: The effect of annealing time on the structure and electrochemical properties of La0.72Nd0.08Mg0.2Ni3.4Al0.1 hydrogen storage alloys was investigated. The alloys were annealed at 1173K for different time, and the results of Rietveld refinement for the XRD data showed that the alloys were composed of Gd2Co7-type, Ce2Ni7-type, Pr5Co19-type, PuNi3-type, LaNi5-type and MgCu4Sn-type phases. Lengthening annealing time obviously promoted the formation of Gd2Co7-type phase which possessed high hydrogen storage capacity, and the largest content of Gd2Co7-type phase was obtained when the alloys were annealed for 20h. The maximum discharge capacity increased from 365.0 (as-cast) to 389.6mAh/g (annealed for 20h), which was ascribed to Gd2Co7-type phase abundance increasing from 35% (as-cast) to a maximum (81.71%, annealed for 20h). Also, the discharge capacity retention over 180 cycles at charge/discharge current density of 300mA/g was remarkably heightened from 56.6% (as-cast) to 80.5% (annealed for 20h). In addition, annealing treatment at 1173K for 6h can enhance high rate discharge ability. [Copyright &y& Elsevier]

Zeolitic Imidazolate Framework-8 (ZIF-8) has attracted great attention from different research fields owing to its high specific surface area and three-dimensional (3D) frameworks. Moreover, ZIF-8 can be converted into nitrogen doping porous carbon material by high temperature calcination. In our report, A N-doped ZIF-8-derived carbon (NC-ZIF) is synthesized at different temperatures as anode material for lithium-ions battery. The NC-ZIF shows regular polyhedral morphology, high specific surface area and porous structure, which providing a fast transportion path, more active sites for lithium-ions and suppressing volume expansion caused by intercalation and deintercalation of lithium-ions. The NC-800 (ZIF-8 annealed at 800 °C) contented 16.2 wt% N and a small amount of ZnO, which exhibits the best lithium storage performance with high capacity and long cycle lifetime. The initial reversible capacity 465.0 mAh∙g−1 is attained, and the capacity remains 440.5 mAh∙g−1 after 100 cycles at a current density of 100 mA∙g−1, with the capacity retention of 94.7%. Even at a high rate of 500 mA∙g−1, the reversible capacity of 211.2 mAh∙g−1 can maintain over 300 cycles with a capacity fading of 0.28% per cycle. Therefore, NC-800 is a very promising anode material for lithium-ion batteries. Image 1 • N-doped ZIF-8-derived carbon was prepared as anode for lithium-ion batteries. • NC-800 has large specific surface area, high N contents and porous structure. • NC-800 exhibits the best electrochemical property, with high capacity and long lifetime. [ABSTRACT FROM AUTHOR]

Dendrite growth is still a problem that high energy density lithium metal batteries must face to commercialize. At present, the introduction of lithiophilic materials on the current collector has proved to be an effective strategy. However, most works are not conducive to the practical application of lithium metal batteries due to the neglect of the preparation cost and the excessive and uncontrollable modifier. Herein, stannic oxide (SnO 2) quantum dots (QDs) were prepared by a simple dehydration reaction to construct a lithiophilic modification layer on the surface of copper foil. In addition, SnO 2 QDs could induce uniform nucleation and growth of lithium ions at the quantum scale. More importantly, when the copper collector was modified by SnO 2 QDs, the symmetric cell could cycle stably for 3200 h at a current density of 1 mA cm−2, which is better than other reports. LiFePO 4 was employed as cathodic materials to fabricate a full battery, which delivered a capacity of 130.4 mAh g−1 with a capacity retention rate of 87.75% at 0.5 C for 200 cycles. Therefore, this work can be extended to practical applications, and help lithium metal batteries to be industrialized. • SnO2 Quantum dots can be prepared easily and on a large scale using a self-growth termination mechanism. • SnO2 quantum dots could induce uniform nucleation and deposition of lithium. • The electrochemical performances are improved by the SnO2 quantum dots modification. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries have attracted enormous attentions as new-generation energy storage devices due to their high theoretical energy density, high theoretical specific capacity, low cost and environmental friendliness. However, polysulfide shuttle and the growth of lithium dendrites significantly restrain the practical application of the Li-S batteries. In this work, a modified PP separator with nanoscale rod-like α-MnO 2 supported on carbon nanotubes was prepared. The α-MnO 2 @CNT modified separator can effectively inhibit the shuttle of polysulfide, enhance the electrochemical activity and accelerate the transfer of ions and electrons. The density functional theory (DFT) calculations demonstrate that α-MnO 2 @CNT can efficiently adsorb and catalyze the conversion of polysulfides. Due to these advantages, the α-MnO 2 @CNT-based Li-S battery delivers a initial discharge capacity of 1469 mAh g−1 at 0.05 C, 1039 mAh g−1 at 0.5 C and the capacity can still maintain 648 mAh g−1 over 500 cycles at 0.5 C (capacity decay rate of 0.075%). Expressly, the capacity decay rate is only 0.022% after 600 cycles at a high current density of 2 C. The excellent performance could be attributed to the α-MnO 2 @CNT modified separator not only accelerating the transmission of electrons but also effectively inhibiting the shuttle of polysulfides. Moreover, this work provides a better idea for practical applications of lithium-sulfur batteries in the future. [Display omitted] • The synthesized α-MnO 2 is in the shape of nanorods. • The α-MnO 2 @CNT composite has good polysulfide adsorption and catalytic conversion ability. • The α-MnO 2 @CNT modified separator shows an excellent long-term cycling stability and rate performance. [ABSTRACT FROM AUTHOR]

Lithium metal has been considered one of the most ideal anode materials for batteries due to its ultrahigh theoretical capacity and energy density. However, the unstable SEI layer and the growth of Li dendrites cause poor cycling performance and even safety hazards, which also severely restrict the commercial application of Li metal batteries. In this paper, a Li-In alloy anode was designed and prepared by mechanical rolling of both Li and In pure metal foils together. Three-dimensional Li-In alloy network structures are formed by mechanical alloying during rolling, and the 3D Li-In alloy structure not only possesses strong lithium affinity but also possesses more interface between the Li matrix and the second phase formed in mechanical alloying, which can promote rapid diffusion at the interface and uniform deposition of lithium ions. As a result, the Li-In electrode shows an extremely low overpotential of approximately 35 mV at a high current density of 5 mA cm−2 during the lithium plating/stripping experiment. In addition, the battery revealed a higher discharge capacity of 295 mAh/g at 0.05 C and capacity retention of 80 % after 150 cycles when the Li-In alloy was used as the anode electrode in a cell with Li 1.2 Ni 0.2 Mn 0.6 O 2 as the cathode. The Li-In alloy can also be used as anode of Li-S battery, the result showed that the capacity decay rate was reduced from 0.22 % to 0.1 % after 200 cycles without any decoration treatment of S cathode except conductive carbon. This work verified that indium in the Li-In alloy can effectively protect the lithium anode and provides an idea for the practical application of lithium metal batteries. [Display omitted] • The Li-In alloy with three-dimensional (3D) interconnected network are formed by mechanical alloying. • The Li-In alloys exhibit strong lithium affinity and rich interfaces. • The alloy anode promotes the uniform deposition of lithium ions to prevent the generation of lithium dendrites. • The alloy electrodes exhibit excellent electrochemical properties for lithium metal batteries. [ABSTRACT FROM AUTHOR]

• The power density of the activated carbon reached 8.8 Wh ∙ kg−1 at 0.25 kW ∙ kg−1. • The activated carbons are rich in carbonyl groups and quinone type oxygen. • The oxygen-rich activated carbons were prepared without oxidation by strong acid. • The fluxing effect of KOH as activation agent was discovered for the first time. Heteroatom-doped activated carbons are ideal materials for energy storage devices. In this work, a series of nitrogen/oxygen codoped activated carbons with an inverse opal-like structure derived from cellulose diacetate are successfully synthesized through hydrothermal reaction and subsequent chemical activation during which the fluxing effect of KOH is discovered for the first time. The introduction of nitrogen and intrinsic oxygen (especially carbonyl and quinone groups) contributes to additional pseudocapacitance. The experimental results show that the obtained product delivers 400.3 F · g−1 at a current density of 1 A · g−1 in a three-electrode system and achieves extraordinary capacity retention of 90% after 10,000 charge-discharge cycles at 5 A · g−1. The energy density reaches as high as 8.8 Wh · kg−1 at a power density of 0.25 kW · kg−1 as symmetric supercapacitors, indicating a promising electrode material for high performance supercapacitors. The simple and cost-effective method requires no extra oxidation and excessive urea and thus provides new approaches for the future design of electrode materials. [ABSTRACT FROM AUTHOR]

Porous activated carbon material is successfully prepared with anthracite through KOH activation. The obtained activated carbon delivers a large specific surface area of 3550.7 m2 g−1 with existence of porous structure. The KOH activation introduces numerous hydroxyl groups on the surface of carbon material, improving the wettability of carbon. As electrode for supercapacitor, the material delivers the high specific capacity of 433 F g−1 at the current density of 0.5 A g−1 and it maintains 230 F g−1 even current density reaches up to 50 A g−1. Especially, as electrode for symmetric capacitor, the porous activated carbon exhibits a high specific capacitance of 280 F g−1 and energy density of 38.9 Wh kg−1 at 0.5 A g−1. The material also displays superior cyclic stability without distinct decay in capacity after 30000 cycles. The porous activated carbon material derived from coal, which embodies characteristics of capacitance behavior, may broaden the horizon of electrode materials and provide application prospect for specialized hybrid supercapacitor applications. Image 1 • The activated carbon produced by anthracite reveals porous microstructure. • The material delivers an ultrahigh specific surface area of 3550.7 m2 g−1. • The material delivers the high energy density of 38.9 Wh kg−1 at 0.5 A g−1. • The facile prepared route provides the train of thought for practical application. [ABSTRACT FROM AUTHOR]